Abstract
Dipyramidole and two new derivatives (RA 233 and 433) were compared as regards their inhibitory action on ADP- and noradrenaline-induced platelet aggregation and adhesiveness in vitro. Aggregation was studied with a turbidometric method allowing accurate kinetic studies. Platelet adhesiveness and aggregation were markedly inhibited by RA 233 and RA 433 (5–50 μg/ml) while dipyridamole (50–100 μg/ml) only had a weak and irregular effect. The rate of disaggregation was not influenced.